Heretofore, cutting tools of pull type rotary mowers have been connected to an undercarriage frame in such a way that their vertical position adjusts to follow the ground level. This results in a drive train for the cutting tools which is very expensive.
In one towed mower design, the tractor hitch is connected to the pulling tractor in such a way that the mower can be swung laterally from a trail behind transport position to a laterally offset operating position. To this end, a drive shaft with universal joints is provided underneath the tractor hitch to transmit power from a tractor power take-off shaft to a gear box on the mowing machine. In this prior art design, a drive shaft universal joint is provided on the mower at a location below the pivot connection of the tractor hitch to the mower. Such a mower design is disadvantageous in that the arc of pivoting of the tractor hitch is narrowly limited, since a maximum angle of refraction for the shaft segments connected by the joint may not be exceeded. As a result, such mowers can be used only on one lateral side of the towing tractor and cannot be pivoted inward, from the lateral operating position, beyond a trail-behind transport position.
U.S. Pat. No. 2,520,107 issued Aug. 22, 1950 to W. Vutz for a Release Mechanism for Mowers shows a mower wherein a square section drive shaft is used rather than a telescoping drive shaft. The square section shaft extends through a pivoted input portion of a bevel gear box. The output shaft of the bevel gear box is connected through a universal joint to an additional intermediate shaft in order to transmit power to the mower. The intermediate shaft is connected through a universal joint to a gear box rigidly mounted on the frame of the cantilever cutter bar mower.
In this prior art mower the ability of the mower to follow the contour of the ground is limited by the cantilevered cutter bar. Even if a rotary blade or disc power were used instead of a cantilever cutter bar, an arrangement results for which the mower as a whole unit would be pivotable only together with the tractor hitch and the drive connection to the tractor for compensating for unevenness in the ground surface. And such disadvantage would still exist even if a pivotable input gear were provided, for example, on the side of the mower.